what is diameter

The diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circumference. It is also the longest chord of the circle and is twice the length of the radius. In more general terms, the diameter is the longest distance across a circle or any other geometric figure. It is denoted by the letter D, and its symbol in engineering is Ø. The formula to calculate the diameter is: Diameter = 2 × Radius, or Diameter = Circumference ÷ π, or Diameter = 2√(Area/π) when the radius, circumference, or area is given